The tuber of the canna canova is used to make food in Thailand, so probably not toxic.
http://www.cannova.info/uk/con...
Lobelia is thought to be a toxic herb - taken in large quantities.
http://medherb.com/Materia_Med...
Fiber optic grass is definitely toxic to cats, and is reported at DG to be toxic in all its parts.
I agree with Deb. Plant the canna with some redbor kale and strawberries, or make it all edible from the getgo. What color is the canna? This could get interesting.
